pub fn new_birthday_probability(n: u32) -> f64 {
    if n >= 365 {
        1f64
    } else if n <= 1 {
        0f64
    } else {
        let mut ret = 1f64;
        for i in 0..n{
            ret *= (365 - i) as f64 / 365f64
        }
        ((1f64 - ret) * 10000f64).round() / 10000f64
    }
}
